In U.S. Pat. No. 3,900,967, issued Aug. 26, 1975, a sill construction is disclosed which includes a base member covered by a cladding of extruded aluminum. This provides a highly satisfactory construction in that the aluminum cladding backed by the base member of molded plastic or the like results in a strong, durable sill which is not unduly expensive since the cladding may be produced as an extruded section cut to length and slipped over previously molded or otherwise formed base members.
Solid brass sills, while generally considered desirable for both reasons of appearance and durability, are substantially more expensive than aluminum clad sills of the type disclosed in the above noted patent and consequently comprise only a small portion of the market.
While a brass clad sill appears theoretically possible and would presumably be significantly less expensive than solid brass sills, as a practical matter brass cladding does not lend itself to manufacture by extrusion to the cross sectional shapes desired, and other methods of producing brass cladding would result in an appreciable increase in manufacturing costs.